Jacquard machines are textile machines which may be used for the weaving of textile materials such as whip cord material or for double shuttle weaving and many Jacquard machines employ what are known as double roller elements.
These double roller elements are located between Jacquard lift bars and the warp threads forming the machine sheds so that, for example, some Jacquard machines which conventionally are two position machines (high shed and low shed) can be converted to three position machines (high shed, middle shed and low shed).
The double roller elements comprise essentially elongated components having rollers at the respective ends thereof and around which connecting cords are trained. The cords which are trained round one of the rollers connect to the lift bars, while the cords which are connected around the rollers at the other ends are connected to the threads which define the warp sheds.
Known double roller elements for this purpose comprise at least six parts, namely two side plates, two guide rollers and their axles. In any particular Jacquard machine there may be vast numbers of such double roller elements and they lie adjacent and in overlapping relationship in a tight pack and it is therefore difficult to change individual double roller elements which have become damaged or worn. The known double roller elements are also expensive and due to the numbers which are used, they are almost as expensive as the Jacquard machine to which they are connected. The known double roller elements typically are made of steel and are comparatively heavy and are not best suited to the high speed movements which are required of these double roller elements. Furthermore the elements tend to collide with one another in use, and a surprisingly high noise level is produced by the elements.
It has been proposed to make double roller elements in plastics material, in order to reduce weight and noise, and in one proposal for a plastic element, the two side members of the element are manufactured in plastics material, and are of identical construction, but to be fitted together they must be turned through 180.degree. relative to one another and then they can be snap fitted, trapping the rollers there between on appropriate axle formations provided in the molding.
These plastic rollers while providing an advance on the heavy steel roller elements, nevertheless have some short comings as related to repair and maintenance thereof. They are difficult to remove from the machine, and the cords cannot be removed from the rollers without prying apart the roller element sides. Due to the environment in which these roller elements are used, this represents a considerable problem because, as mentioned, above the elements are tightly packed in the machine.
Another problem is that if only one roller is to be replaced, the entire element must be opened up and the other roller may fall and become lost.